In forming metallic cups from which can bodies are eventually produced by the draw and iron process, the cups are formed in a cupping press at high speed and ejected vertically downwardly onto a conveying surface at an entry point of the conveying surface. Due to the high speed nature of these cupping presses, it is imperative that a cup be removed from the entry point of the conveyor quickly so that the next succeeding cup does not come into contact with the previous cup, resulting in a jam of the conveying system and necessitating shutdown of the press for clearing.
Traditionally, the conveying mechanisms positioned beneath cupping presses have been endless belt conveyors having a driven pulley, an idler pulley, an endless belt positioned around the pulleys and a driving mechanism. Such conveying mechanisms require frequent adjustment for proper tension of the belt, include numerous moving parts subject to failure and rely solely upon friction between the belt and the object being conveyed to affect high speed removal from the entry point of the conveying surface.
Unfortunately, slippage of the objects on the belt often results in an object not fully clearing the entry point of the conveyor prior to a subsequent object being dropped thereon, resulting in a jam of the system.
In order to overcome the slippage problems of frictional conveyors, it has been proposed to supplement the friction-induced acceleration with an initial acceleration provided by an air jet. Such a solution has not been successful, as the acceleration provided by the air jet along the frictional surface often results in tipping or other inconsistent movement of the objects along the conveyor, resulting in jamming of the conveyor system.
It is thus a primary object of the present invention to provide a conveying mechanism which does not rely upon friction between the object being conveyed and the conveying surface for conveyance of the object
It is also an object of the present invention to eliminate the belt conveyors commonly employed with cupping presses in order that their adjustment and maintenance requirements be eliminated
It is also a primary objective of the present invention to provide a conveying mechanism in which positive initial acceleration from the entry point of the objects on the conveying surface is provided along a frictionless conveying surface.
It is also common in the can making art, as well as in other fields, to employ air tables, or air conveyors, to move can bodies throughout the can making plant. While such air tables do provide movement for such objects, it is heretofore been unknown to employ air tables in a setting where high speed initial acceleration of the objects was required.
It is thus an additional primary objective of the present invention to provide an air conveying system which includes initial high speed acceleration of the objects along the conveying surface.
An additional limitation of the known belt conveyors, especially for those employed for conveying metallic cups from cupping presses, is the ability of such systems to properly sense cups at their entry point to the conveyor. There is limited space beneath a cupping press and belt conveyors do not permit sensors to be positioned beneath the conveying surface. Thus, metal sensors must be located above the conveying surface and behind the entry point. Unfortunately, in this position, the sensor sees only a portion of the cylindrical sidewall of the cup. This presents two conflicting problems. If the sensor is set to always see the cup, and if the cup is not removed from the entry point quickly enough, the sensor gives a false jam signal, resulting in shutdown of a properly operating system. However, if false jam signals are not desired, then the sensor must be set such that it will not always see cups entering the system, resulting in a false "no cup" signal, again resulting in shutdown of a properly operating system.
It is thus an additional object of the present invention to provide a conveying system in which the metal sensor is positioned to see a relatively large, flat metallic surface, thus improving the sensing reliability of the system.